1. Field of the Invention
The present invention relates to a mobile wireless terminal apparatus for use in a wireless communication system which provides a plurality of wireless connection methods.
2. Description of the Related Art
There has been developed a system wherein a mobile wireless terminal apparatus, which supports two or more different wireless connection methods, periodically receives a paging signal which is sent by a certain wireless communication method, thereby waiting for signal reception with respect to a plurality of wireless communication systems at the same time. In this system, there are two cases: a case in which base stations of different wireless connection methods are installed at geometrically the same position, and a case in which such base stations are installed at different positions.
As the above-described wireless connection methods, the following examples are thinkable: CDMA2000 1x method (see, e.g. 2001 3G Workshop Part 2 by Agilent Technologies, Jan. 16, 2001, pp. 2-35); EV-DO method (see, e.g. 2001 3G Workshop Part 2 by Agilent Technologies, Jan. 16, 2001, pp. 36-50); and LTE (Long Term Evolution) method (see, e.g. Erik Dahlman, Academic Press, 2007, pp. 277-369). In the case of these examples, as regards the CDMA2000 1x method and EV-DO method, the population coverage of the service areas thereof has already reached about 95%. On the other hand, in the LTE method which is newly developed, it is expected that at the beginning of practical use, services will be developed successively from urban areas with high population densities.
In general, a mobile wireless terminal apparatus periodically searches for a nearby base station which enables good-quality communication. If the mobile wireless terminal apparatus has found a nearby base station which is better than the base station that is used for signal reception wait, handover is made to the nearby base station. For example, in the case of a mobile wireless terminal apparatus which supports two wireless connection methods A and B, if signal reception has occurred in the wireless connection method B that is other than the wireless connection method A that is used for signal reception wait, in order to quickly establish the connection by the wireless connection method B, it is necessary to periodically search for the nearby basic station with respect to the wireless connection method B as well as the wireless connection method A.
However, it is not desirable to periodically search for a nearby base station with respect to a plurality of wireless connection methods, since this increases the power consumption at the time of signal reception wait.
In the conventional mobile wireless terminal apparatus which supports a plurality of wireless connection methods, there is a problem that the power consumption at the time of signal reception wait is large, since a nearby base station is periodically searched for with respect to each of the plural wireless connection methods.